Improve error handling re: homedir expansion
Improve error handling re: homedir expansion

Useful if the HOME envvar is not set because `vault` was launched in a clean environment (e.g. `env -i vault ...`).

joelthompson/vault,careyblack/vault,martin-ducar-gd/vault,jmhardison/vault,peteryhwong/vault,careyblack/vault,kenbreeman/vault,mymercurialsky/vault,wjam/vault,kenbreeman/vault,Aloomaio/vault,geckoboard/vault,chrishoffman/vault,hashicorp/vault,rnaveiras/vault,hartsock/vault,LolalyLuo/vault,doodles526/vault,rnaveiras/vault,LolalyLuo/vault,annanay25/vault,martin-ducar-gd/vault,quixoten/vault,annanay25/vault,memory/vault,kingland/vault,Aloomaio/vault,jam-pot/vault,lirao/vault,geckoboard/vault,geckoboard/vault,mgk/vault,hashicorp/vault,Aloomaio/vault,jmhardison/vault,hashicorp/vault,quixoten/vault,quixoten/vault,mhurne/vault,MonsantoCo/vault,geckoboard/vault,mhurne/vault,ryon/vault,lemondrank/vault,rnaveiras/vault,mgk/vault,cimarron-pistoncloud/vault,geckoboard/vault,kingland/vault,Caiyeon/vault,jmhardison/vault,michaelansel/vault,annanay25/vault,skippy/vault,joelthompson/vault,michaelansel/vault,jgcallero/vault,joelthompson/vault,lirao/vault,peteryhwong/vault,naunga/vault,mymercurialsky/vault,hartsock/vault,hartsock/vault,Aloomaio/vault,chrishoffman/vault,jgcallero/vault,deverton/hashicorp-vault,wjam/vault,annanay25/vault,kenbreeman/vault,hashicorp/vault,lemondrank/vault,deverton/hashicorp-vault,jmhardison/vault,jmhardison/vault,Banno/vault,doodles526/vault,Caiyeon/vault,ryon/vault,hartsock/vault,jam-pot/vault,naunga/vault,danielsomerfield/vault,tallpauley/vault,kenbreeman/vault,quixoten/vault,rnaveiras/vault,kingland/vault,tallpauley/vault,kingland/vault,cimarron-pistoncloud/vault,skippy/vault,mgk/vault,hartsock/vault,careyblack/vault,memory/vault,annanay25/vault,danielsomerfield/vault,hashicorp/vault,kingland/vault,joelthompson/vault,careyblack/vault,careyblack/vault,hashicorp/vault,Banno/vault,kenbreeman/vault,MonsantoCo/vault,mgk/vault,rnaveiras/vault